Your eye health is very important to know and keep track of. Going to regularly scheduled eye exams with your ophthalmologist will make sure that your eyes are always the best that they can be. During your exam, the doctor will look at all parts of your eye to make sure they’re functioning well. They will also check for diseases like glaucoma, cataracts, and diabetic eye disease. These diseases and other issues with your eyes can pose a danger to your eyesight if left untreated. It’s important to have a basic understanding of the anatomy of the eye so you can understand what your ophthalmologist may say to you during an exam in case there’s a serious issue.

The eye can be split into two parts: The outer eye and the inner eye. The eye is a very complex organ that can be hard to understand. We want to give you a crash course on the most basic elements of the eye so that you can have a better understanding of how the eye works. If you have any questions about the more specific aspects of the eye or have any confusion when your ophthalmologist is explaining something, don’t be afraid to ask questions. Your eye doctor is here to help you.

The Outer Eye

Cornea: The cornea is the transparent outer covering of the eye. Light enters through the cornea and is focused through the fluid-filled space behind it.

Sclera: The sclera is the white part of the eye that surrounds the cornea and maintains the overall shape of the eye. It may seem small, however, the sclera ranges from the cornea all the way to the optic nerve. It’s 80% of the surface area of your eye.

Iris: The iris is the colored part of the eye. The muscles in the iris dilate (widen) and constrict (narrow) the pupil to control how much light reaches the back of your eye.

Pupil: The pupil is the dark hole in the center of the eye. Light travels through the pupil to the lens.

Lens: The lens focuses light on the back of the eye. The ciliary body and muscles surrounding the lens relax and contract to change their shape in order to focus on near and far objects. To the surprise of many, the lens only accounts for 30% of your eye’s focusing power while the cornea does the other 70%.

Conjunctiva: The conjunctiva is a clear, thin membrane that covers the front surface of the eye and the inner surface of the eyelids. It keeps the eye lubricated and protects the eye from dust and debris.

  • Bulbar conjunctiva: This part of the conjunctiva covers the front of the sclera and stops before the cornea.
  • Palpebral conjunctiva: This part of the conjunctiva covers the inner surface of the upper and lower eyelids.

The Inner Eye

Vitreous humor: Vitreous humor is a substance the consistency of jelly that fills the space between the lens and the back of the eye. Light passes from the cornea and lens, through the vitreous, and then to the retina.

Retina: The retina is a light-sensitive tissue at the back of the eye that provides you with vision. It is filled with photoreceptors that process light and transmit it to the brain.

  • Rods and cones: Rods and cones are two kinds of photoreceptors in the eye. Rods perceive black and white while cones perceive color.

Macula: The macula is the area of the retina responsible for our central vision. This is where most of the cones in the retina reside.

Peripheral retina: The peripheral retina is the area of the retina responsible for our peripheral vision. There are more rods than cones in the peripheral retina.

Optic nerve: The optic nerve is the channel through which the retina sends those electrical impulses to the brain. It is made up of millions of nerve fibers that transmit energy to the visual cortex in the brain.


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